What is the best way to remove a stripped head bolt?
 

I was moving along on my 603 head removal until I stripped out one of the head bolts. Maybe it was damaged or I wasn't careful enough, but those 12 point "triple square" bolts seem to be pretty fragile. Anyway I am stuck in the mud until I can get this one out.
Is there some kind of extractor to use or should I just get a 3/16 drill bit and drill down into the cap of the bolt until it takes the top off?
Also are the bolts made of hardened steel and do I need to use a special bit?
The only other thing I need to do to lift the head off the car is to remove the connection on the right side where the heater pipe goes into the head. I turned that large connector about 3 times and now it is getting harder to turn. Is there some kind of trick to it?

We need to know more exactly what the bolt looks like... can you post a picture ?

It may be that you can put a nut on top of it and use high alloy rod to weld it to the top of the bolt.... but we have to be sure we know what your situation is first...

Basically, you have to drill the head of the bolt until it pops off. Wear eye protection because as you drill into the bolt head, the full force of the bolt is going to blow the head of the bolt backwards when you cut it from the bolt shaft.

Once the head of the bolt is gone, the shaft of the bolt should be easy to turn and spin right up out of the block.

Use left hand drill

Hughet,

Don't grab the drill just yet. If you have a clear shot at the head of the bolt, drive down to the nearest Sears store and buy a set of bolt extractors. They look kind of like sockets that fit around the head of the bolt and have left-handed knurled splines that dig into the bolt head as you back it out. They sell half sets that are all odd or even sized or you can buy the whole set. A half set costs about $20. Bring a head bolt with you to buy the right size. Even if the extractors don't work on this bolt, you won't regret buying them because they really come in handy. Good luck!

I think what you are looking for is a stud extractor sized for the outside of the bolt's head. Is there enough area on the head of the bolt for a stud extractor to work?

There's a metal clip that holds the coolant pipe in. It pops right off with a small screwdriver.

someone suggested
 

forcing a larger us sized allen into the hole by driving it in with a big hammer. in using these allen head bolts it is absolutely essential that the hole is cleaned out and the allen driven in to the bottom. sorry. i will get off the soap box now.

good luck

tom w

Thanks for the help
 

I want to thank everyone for the help. I ended up drilling the head bolt out with a 3/8" heavy duty drill bit.
I made a pin puller from a 3 1/2 inch long 3/4 inch pipe nipple with ends and a 5 pound weight from a barbell set. I drilled a hole in one of the ends for the 6 mm bolt, hooked it up and after heating the area got it out with a few wham bams.